In the valve devices (hereinafter referred to as swing valves) of Patent Documents 1 and 2, an axis is provided that passes through a lateral side of an opening of a discharge pipe and is parallel to the opening. The swing valve rotates a lid portion about the axis to open/close the opening. At this time, an end portion of the lid portion rotates so as to draw an arc toward the downstream side of the opening.
Thus, in the swing valve, a hangover is increased. The hangover is the degree to which a trajectory of the lid portion opening/closing the opening projects toward the downstream side of the opening. That is, a space required for opening/closing the opening increases. In addition, a force required for opening/closing the opening increases. There has been known a phenomenon called chattering in which during closing of the opening, the lid portion opens/closes the opening due to an increase or decrease in air pressure inside the exhaust pipe. In the swing valve, a large force is applied to the lid portion when the opening is closed. Thus, abnormal noise generated by collision of the lid portion with the exhaust pipe at the time of occurrence of chattering increases.